Systems and methods for glass particle detection

ABSTRACT

A particle detection system includes a light source configured to emit a light beam into a cylindrical glass article when the cylindrical glass article is imaged by the glass particle detection system. The light beam is directed along a beam propagation axis that is perpendicular to a longitudinal axis of the cylindrical glass article. The particle detection system further includes a first polarizer positioned between the light source and the cylindrical glass, a camera configured to capture an image of the light beam reflected from the cylindrical glass article, and an analyzer positioned between the cylindrical glass article and the camera. An optical axis of the camera is perpendicular to the beam propagation axis of the light source.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/425,277, filed on Nov. 22, 2016, the entire contents of which areherein incorporated by reference.

BACKGROUND Field

The present specification generally relates to detecting glass articledefects and, more particularly, to detecting particles on inner surfacesof cylindrical glass articles.

Technical Background

The manufacture of glass tubing products (e.g., tubes, syringes, andvials) for use in the pharmaceutical industry sometimes leads toparticles or fibers that adhere to the exposed surfaces of the glasstubing products. For example, particles may be attached to the innerwall or the outer wall of the glass tubing products. Fiber and particledefects of this type are a result of the converting process thatinvolves scoring of a long cylindrical tube to produce smallerindividual parts. These defects may be particularly undesirable if theyare on the inside of a syringe where they might come loose andcontaminate the medical product contained with the syringe or even beinjected to a human body. This type of defect was responsible for over25% of FDA recalls since 2013 and is a major source of lot yield loss inthe industry.

Accordingly, alternative glass defect detection systems are desired.

SUMMARY

According to one embodiment, a particle detection system includes alight source configured to emit a light beam into a cylindrical glassarticle when the cylindrical glass article is imaged by the glassparticle detection system. The light beam is directed along a beampropagation axis that is perpendicular to a longitudinal axis of thecylindrical glass article. The particle detection system furtherincludes a first polarizer positioned between the light source and thecylindrical glass, a camera configured to capture an image of the lightbeam reflected from the cylindrical glass article, and an analyzerpositioned between the cylindrical glass article and the camera. Anoptical axis of the camera is perpendicular to the beam propagation axisof the light source.

According to another embodiment, a method for detecting particles on acylindrical glass article includes directing a light beam through afirst polarizer into the cylindrical glass article along a beampropagation axis that is perpendicular to a longitudinal axis of thecylindrical glass article, the light beam polarized by the firstpolarizer producing light scattered by one or more particles on theinner wall of the cylindrical glass article, capturing, by a camerahaving an optical axis perpendicular to the beam propagation axis, animage of the light beam reflected from the cylindrical glass articleincluding the scattered light via an analyzer, the analyzer locatedbetween the cylindrical glass article and the camera, and a polarizationaxis of the first polarizer being oriented at about 90 degrees relativeto a polarization axis of the analyzer, and determining whether aparticle is present in the image.

According to another embodiment, a glass particle detection systemincludes a light source configured to emit a light beam into acylindrical glass article when the cylindrical glass article is imagedby the glass particle detection system, the light beam being directedalong a beam propagation axis that is parallel to a longitudinal axis ofthe cylindrical glass article and illuminating an inner wall of thecylindrical glass article, and a camera configured to capture an imageof the light beam, an optical axis of the camera being perpendicular tothe beam propagation axis of the light source, a focal plane of thecamera being located proximate to the inner wall of the cylindricalglass article.

According to another embodiment, a method for detecting particles on acylindrical glass article includes directing, by a light source, a lightbeam into the cylindrical glass article along a beam propagation axisthat is parallel to a longitudinal axis of the cylindrical glassarticle, the light beam illuminating an inner wall of the cylindricalglass article, capturing, by a camera, an image of the light beamreflected from the cylindrical glass article, an optical axis of thecamera being perpendicular to the beam propagation axis of the lightsource, and a focal plane of the camera being located proximate to theinner wall of the cylindrical glass article, and determining whetherillumination from the cylindrical glass article is present within theimage.

According to another embodiment, a glass particle detection systemincludes a light source configured to emit a ring light, the ring lightbeing directed along a beam propagation axis that is perpendicular to alongitudinal axis of a cylindrical glass article when the cylindricalglass article is imaged by the glass particle detection system, a beamsplitter configured to reflect the ring light and change a direction ofthe ring light to a direction parallel to the longitudinal axis of thecylindrical glass article, a center of the ring light reflected by thebeam splitter being aligned with the longitudinal axis of thecylindrical glass article, a first polarizer positioned between thelight source and the beam splitter, a camera configured to capture animage of the ring light reflected from the cylindrical glass article, anoptical axis of the camera being parallel with the longitudinal axis ofthe cylindrical glass article, and an analyzer positioned between thecylindrical glass article and the camera.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from that description or recognized by practicing theembodiments described herein, including the detailed description whichfollows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various embodiments describedherein, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a glass particle detection system accordingto one or more embodiments shown and described herein;

FIG. 2A depicts a partial side view of the glass particle detectionsystem of FIG. 1 according to one or more embodiments shown anddescribed herewith;

FIG. 2B depicts an image of light scattered from glass particlesaccording to one or more embodiments shown and described herewith;

FIG. 2C depicts the image of FIG. 2B after being processed according toone or more embodiments shown and described herewith;

FIG. 3A depicts a ray diagram of an observer viewing a glass articleincluding a particle on the inner wall of the glass article according toone or more embodiments shown and described herewith;

FIG. 3B depicts an image of a focal plane crossing the glass articleincluding a particle according to one or more embodiments described andshown herewith;

FIG. 3C depicts an image of a focal plane crossing the glass articleincluding a particle according to another embodiment described and shownherewith;

FIG. 4A illustrates an exemplary image captured by a camera withoutusing a polarizer and an analyzer according to one or more embodimentsdescribed and shown herewith;

FIG. 4B illustrates an exemplary image captured by the camera using thepolarizer and the analyzer according to one or more embodimentsdescribed and shown herewith;

FIG. 5A depicts a side view of a glass particle detection systemaccording to one or more embodiments described and shown herewith;

FIG. 5B depicts a front view of a glass particle detection system ofFIG. 5A according to one or more embodiments described and shownherewith;

FIG. 6 depicts a camera configuration for determining the location ofparticles on a glass article according to one or more embodimentsdescribed and shown herewith;

FIG. 7A depicts light scattered from an internal particle of a glassarticle according to one or more embodiments described and shownherewith;

FIG. 7B depicts light scattered from an external particle of a glassarticle according to one or more embodiments described and shownherewith;

FIG. 8A depicts a sample image captured by a camera using conventionalbacklighting according to one or more embodiments described and shownherewith;

FIG. 8B depicts a sample image captured by a camera using the lightsource shown in FIG. 6 according to one or more embodiments describedand shown herewith;

FIG. 9 schematically depicts a glass particle detection system accordingto one or more embodiments shown and described herein; and

FIG. 10 depicts an image of a ring light reflected from the glassarticle according to one or more embodiments described and shownherewith.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of systemsand methods for detecting particles in cylindrical glass articles. Glassparticles can be present on both the inner wall and the outer wall ofthe cylindrical glass articles. In some embodiments, only the presenceof particles on the inner wall constitutes a reason for part rejectionbecause particles on the inner wall of the cylindrical glass articles(e.g., tubes, syringes, vials) might come loose and contaminate themedical product inside the cylindrical glass article or even be injectedto a human body. For this reason, a method for internal/externalparticle detection selectivity is desirable. One example of a glassparticle detection system is schematically depicted in FIG. 1. The glassparticle detection system may include a light source configured to emita light beam into a cylindrical glass article. The light beam isdirected along a beam propagation axis that is perpendicular to alongitudinal axis of the cylindrical glass article. The glass particledetection system further includes a first polarizer positioned betweenthe light source and the cylindrical glass article, a camera configuredto capture an image of the light beam reflected from the cylindricalglass article, and an analyzer positioned between the cylindrical glassarticle and the camera. An optical axis of the camera is perpendicularto the beam propagation axis of the light source. Various embodiments ofglass particle detection systems and methods for detecting particles onthe inner wall of a cylindrical glass article will be described infurther detail herein with specific reference to the appended drawings.

One process for manufacturing cylindrical glass articles is the Velloprocess. The Vello process may be used to form cylindrical glassarticles by flowing molten glass around a bell head of a known diameterwhile simultaneously flowing a gas, such as air, through the bell head.The bell head is positioned and supported within an opening of a glassdelivery tank containing molten glass using a bell support. The bellsupport is also used to supply the gas to the bell head. The bell head,in conjunction with the flowing gas, forms the molten glass intocylindrical glass article with a desired wall thickness.

The high temperature of the molten glass may cause degradation of themetallic material of the bell support such as, for example, scaling,oxidation, and blistering. Particles resulting from the degradation ofthe metallic material may be carried through the bell support and bellhead by the flowing gas and into the soft glass of the resultingcylindrical glass article. The particles may become embedded in theglass creating inclusion defects that may result in all or portions ofthe cylindrical glass article being discarded, decreasing manufacturingefficiencies and increasing manufacturing costs. The methods and systemsdescribed herein detect such particles. The systems and methodsdescribed herein may be used to detect defects on glass articles formedby the Vello process, or any other cylindrical glass article formingprocess.

FIG. 1 schematically depicts a glass particle detection system 100according to one or more embodiments shown and described herein. Theglass particle detection system 100 includes a light source 110, acamera 120, a polarizer 130, an analyzer 140, and a glass article 150.The glass article 150 may be a cylindrical glass article such as a tube,a syringe, a vial, etc. The glass article 150 has a longitudinal axis190 which is parallel to the z axis in FIG. 1. The glass article isfixed to a holder 160 which is attached to a linear actuator 170.

The light source 110 may be a laser emitting a light beam 112. The lightbeam 112 may be a line light. The light source 110 may be a diode laserincluding an array of laser diodes which project a line of light. Thelight beam 112 may be directed along a beam propagation axis 194 that isperpendicular to the longitudinal axis 190 of the glass article 150. Thelight beam 112 may be orthogonal to a y-z plane in FIG. 1. In someembodiments, the light beam 112 may be directed in a direction notperpendicular to the longitudinal axis 190 of the glass article 150. Forexample, the light beam 112 may be directed at an angle of less than 90degrees with respect to the longitudinal axis 190. In some embodiments,the width of the light beam 112 (in terms of the y direction of FIG. 1)may be larger than the outer diameter of the glass article shown in FIG.2B such that the light beam 112 is projected on the whole cross section(parallel the x-y plane in FIG. 1) of the glass article 150. In someembodiments, the light source 110 is a light source other than a laser,such as an LED light source, a visible light source, an infrared lightsource, etc.

The polarizer 130 may be positioned between the light source 110 and theglass article 150 such that the light beam 112 from the light source 110passes through the polarizer 130 at a normal direction of the polarizer130 (i.e., +x axis direction). The polarizer 130 polarizes thenon-polarized light beam 112 according to a polarization axis of thepolarizer 130 and outputs a polarized light 114. The polarized light 114may produce less glare when reflecting from the glass article 150compared to the non-polarized light beam 112.

The glass article 150 may scatter the polarized light 114. The scatteredpolarized light may direct to various directions including a directiontoward the camera 120. If the glass article 150 includes any particleson its surface, the polarized light 114 is scattered by the particles.In some embodiments as shown in FIG. 1, the glass article 150 may havean internal particle 156 attached on the inner wall 152 of the glassarticle 150 and an external particle 158 attached on the outer wall 154of the glass article 150. The polarized light 114 may be scattered bythe external particle 158 and the internal particle 156. The scatteredlight may direct to various directions including a direction toward thecamera 120.

The polarization direction of the polarized light 114 is changed whenthe polarized light 114 is scattered by the external particle 158 or theinternal particle 156. For example, the light 116 that was scattered bythe internal particle 156 is polarized in a different direction than thepolarization direction of the polarized light 114. Similarly, the light118 that was scattered by the external particle 158 is polarized in adifferent direction than the polarization direction of the polarizedlight 114. In contrast, the polarization direction of the polarizedlight 114 is not changed when the polarized light 114 scatters on theglass article 150 where no particle is present. For example, the light119 which was scattered by the glass article 150 is polarized in thesame direction as the polarized light 114.

The analyzer 140 is positioned between the glass article 150 and thecamera 120. The analyzer 140 may be a polarizer that polarizes anincident light. The analyzer 140 may have similar light opticalcharacteristics (e.g., polarization) as the polarizer 130. Thepolarization axis of the analyzer 140 may be oriented to a differentdirection than the polarization axis of the polarizer 130. For example,the polarization axis of the analyzer 140 may be oriented at about ±90degrees relative to the polarization axis of the polarizer 130. Thus,the polarized light 114 polarized according to the polarization axis ofthe polarizer 130 cannot pass through the analyzer 140 because thepolarized light 114 is polarized in a direction orthogonal to thepolarization axis of the analyzer 140. Similarly, the light 119 whichwas reflected from the glass article 150 cannot pass through theanalyzer 140 because the light 119 is polarized in a directionorthogonal to the polarization axis of the analyzer 140.

In contrast, the light 118 that was scattered by the external particle158 is polarized in a direction that is not orthogonal to thepolarization axis of the polarized light 114. For example, thepolarization direction of the light 118 may be different from thepolarization axis of the polarizer 130, but not orthogonal to thepolarization axis of the analyzer 140. Thus, a portion of the light 118would pass through the analyzer 140 because the difference between thepolarization direction of the light 118 and the polarization axis of theanalyzer 140 is not 90 degrees, i.e., not orthogonal. Similarly, thelight 116 that was scattered by the internal particle 156 is polarizedin a direction that is not orthogonal to the polarization axis of theanalyzer 140. For example, the polarization direction of the light 116may be different from the polarization axis of the polarizer 130, butnot orthogonal to the polarization axis of the analyzer 140. Thus, aportion of the light 116 would pass through the analyzer 140 because thedifference between the polarization direction of the light 116 and thepolarization axis of the analyzer 140 is not 90 degrees, i.e., notorthogonal. In this regard, only light that is scattered by particles onthe outer wall 154 or the inner wall 152 of the glass article 150 canpass through the analyzer 140.

The camera 120 may capture an image of the light beam reflected from theglass article 150. The camera 120 may be any device having an array ofsensing devices capable of detecting radiation in an ultravioletwavelength band, a visible light wavelength band, or an infraredwavelength band. The camera 120 may have a focal plane that is locatedwhere the polarized light 114 overlaps with the glass article 150. Thefocal plane may be parallel to the x-y plane in FIG. 1. The camera 120may include an optical lens 122. The camera 120 may capture an image ofthe light beam reflected from the glass article 150 including theexternal particle 158 and the internal particle 156, which isillustrated, for example, in FIG. 2A. The optical axis 192 of the camera120 may be orthogonal to the beam propagation axis 194. The optical axis192 of the camera 120 may be parallel with the longitudinal axis 190 ofthe glass article 150. In some embodiments, the optical axis 192 of thecamera 120 may be co-located with the longitudinal axis 190 of the glassarticle 150. In another embodiment, the optical axis 192 of the camera120 may not be parallel with the longitudinal axis 190 of the glassarticle 150, but the optical axis 192 may be crossed with thelongitudinal axis 190 of the glass article 150 at a point proximate tothe focal plane of the camera 120.

The linear actuator 170 may move in a vertical direction (+/−zdirection) to move the glass article 150 in the vertical direction. Asthe linear actuator 170 moves glass article 150 in the verticaldirection, the light source 110 can direct the polarized light 114 tothe entire surface of the glass article 150. The camera 120 can alsocapture images of the light beam reflected from each and every portionof the wall of the glass article 150.

The camera 120 may communicate with a computing device 180 via acommunication path 186. The computing device 180 may include one or moreprocessors 182, and a memory module 184. Each of the one or moreprocessors 182 may be any device capable of executing machine readableinstructions. Accordingly, each of the one or more processors 182 may bea controller, an integrated circuit, a microchip, a computer, or anyother computing device. The one or more processors 182 are coupled tothe communication path 186 to communicate with the camera 120. Thecamera 120 may transmit the captured image of the light beam reflectedfrom the glass article 150 to the processor 182 of the computing device180 via the communication path 186. In some embodiments, the camera 120may include the one or more processors 182 and the memory module 184. Insome of such embodiments, the camera 120 may capture an image of thelight beam, process the image by the one or more processors 182, andstore the processed image in the memory module 184.

The communication path 186 may be formed from any medium that is capableof transmitting a signal such as, for example, conductive wires,conductive traces, optical waveguides, or the like. In some embodiments,the communication path 186 may facilitate the transmission of wirelesssignals, such as WiFi, Bluetooth, Near Field Communication (NFC) and thelike. Moreover, the communication path 186 may be formed from acombination of mediums capable of transmitting signals. In oneembodiment, the communication path 186 comprises a combination ofconductive traces, conductive wires, connectors, and buses thatcooperate to permit the transmission of electrical data signals tocomponents such as processors, memories, sensors, input devices, outputdevices, and communication devices. Accordingly, the communication path186 may comprise a vehicle bus, such as for example a LIN bus, a CANbus, a VAN bus, and the like. Additionally, it is noted that the term“signal” means a waveform (e.g., electrical, optical, magnetic,mechanical or electromagnetic), such as DC, AC, sinusoidal-wave,triangular-wave, square-wave, vibration, and the like, capable oftraveling through a medium.

The one or more memory modules 184 may comprise RAM, ROM, flashmemories, hard drives, or any device capable of storing machine readableinstructions such that the machine readable instructions can be accessedby the one or more processors 182. The one or more memory modules 184may store images captured by the camera 120. The captured images may beprocessed by the one or more processors 182 before being stored in theone or more memory modules 184. The machine readable instructions maycomprise logic or algorithm(s) written in any programming language ofany generation (e.g., 1 GL, 2 GL, 3 GL, 4 GL, or 5 GL) such as, forexample, machine language that may be directly executed by theprocessor, or assembly language, object-oriented programming (OOP),scripting languages, microcode, etc., that may be compiled or assembledinto machine readable instructions and stored on the one or more memorymodules 184. Alternatively, the machine readable instructions may bewritten in a hardware description language (HDL), such as logicimplemented via either a field-programmable gate array (FPGA)configuration or an application-specific integrated circuit (ASIC), ortheir equivalents. Accordingly, the methods described herein may beimplemented in any conventional computer programming language, aspre-programmed hardware elements, or as a combination of hardware andsoftware components.

FIG. 2A depicts a partial side view of the glass particle detectionsystem in FIG. 1 according to one or more embodiments shown anddescribed herewith. The camera 120 may have a field of view 124 whichextends beyond an outer wall 154 of the glass article 150. The camera120 may have a depth-of-field that is one to five times larger than thethickness of the wall of the glass article 150. For example, the camera120 may have a depth-of-field of 4 mm. The camera 120 has the opticalaxis 192 which may be parallel or co-located with the longitudinal axis190 of the glass article 150.

FIG. 2B depicts an image of light reflected from the glass particles 156and 158 according to one or more embodiments shown and describedherewith. The camera 120 may have a field of view 124 which extendsbeyond the outer wall 154. In this embodiment, the image 200 illustratesa view of a focal plane of the camera 120. The image 200 may depict theinner wall 152 and the outer wall 154 of the glass article 150, a wallthickness 230 of the glass article 150, a region of interest 240, aninternal particle 156 and an external particle 158.

The outer wall 154 and the inner wall 152 are illustrated in the image200 in FIG. 2B for reference only, and the actual image may not includethe outer wall 154 and the inner wall 152. As described above, becausethe polarization direction of the light scattered by particles ischanged by certain degrees, the light scattered by the internal particle156 and the external particle 158 can pass through the analyzer 140 andreach the camera 120. Thus, both the internal particle 156 and theexternal particle 158 may be visible to the camera 120, and included inthe image 200.

The region of interest 240 may be defined by an inner circle 206 and anouter circle 208. The outer circle 208 may be located between the innerwall 152 and the outer wall 154 of the glass article 150. The innercircle 206 may be located inside the inner wall 152 of the glass article150. The radius of the inner circle 206 may be set less than the radiusof the inner wall 152. For example, the radius of the inner circle 206may be about 90%-95% of the radius of the inner wall 152. In anotherexample, the radius of the inner circle 206 may be about 80% of theradius of the inner wall 152. By defining the region of interest by theouter circle 208 and the inner circle 206, the external particle 158 maybe located outside the region of interest 240 whereas the internalparticle 156 may be located inside the region of interest 240. Theindication of the region of interest 240 may be embedded to an actualimage captured by the camera 120 in order to facilitate determiningwhether a particle is present on the inner wall of the glass article150. In embodiments, the one or more processors 182 may determinewhether any particle is present within the region of interest 240 of theimage captured by the camera 120. If it is determined that a particle ispresent within the region of interest 240, the one or more processors182 may determine that the particle is attached to the inner wall of theglass article 150. The one or more processors 182 may indicate that theglass article 150 should be rejected based on the determination. Theindication of rejection may be stored in the one or more memory modules184 along with the identification of the glass article 150. If it isdetermined that no particle is present within the region of interest240, the one or more processors 182 may determine that no particle ispresent on the inner wall of the glass article 150. The determinationmay be stored in the one or more memory modules 184 along with theidentification of the glass article 150.

FIG. 2C depicts the image of FIG. 2B after being processed according toone or more embodiments shown and described herein. The captured image200 may be processed by the camera 120 to remove any illumination,noise, particles, etc. outside the region of interest 240 whilemaintaining content or illumination within the region of interest 240.In some embodiments, the camera 120 may send the captured image to theone or more processors 182 and the one or more processors 182 mayimplement image processing on the captured image to remove anyillumination, noise, particles, etc. outside the region of interest.With this processing, the external particle 158 shown in the camera viewis removed while the internal particle 156 remains in the region ofinterest 240. Then, the one or more processors 182 may determine whetherany particle is present within the region of interest 240 on theprocessed image 280. If it is determined that a particle is presentwithin the region of interest 240 on the processed image 280, the one ormore processors 182 may determine that the particle is attached to theinner wall of the glass article 150. The one or more processors 182 mayindicate that the glass article 150 should be rejected based on thedetermination. The indication of rejection may be stored in the one ormore memory modules 184 along with the identification of the glassarticle 150. If it is determined that no particle is present within theregion of interest 240 on the processed image 280, the one or moreprocessors 182 may determine that no particle is present on the innerwall of the glass article 150. The determination may be stored in theone or more memory modules 184 along with the identification of theglass article 150.

In embodiments, various processing methods may be implemented on thecaptured image in order to remove undesirable data on the image. Forexample, a threshold filter may be applied to the captured image toremove most of the unwanted artifacts from the image. The processing mayalso convert the captured image to a binary image. For example,particles captured on the image may be converted to white dots whereasthe rest of the image may be converted to black dots. A particle filtermay be applied to the captured image to remove any artifacts that do notpersist after image processing. The various processing may effectivelyremove features in the image that are too small to be real defects.

With respect to particles in the region of interest 240, the camera 120or the one or more processors 182 may implement processing the image toenlarge the particles in the image relative to the background structure.For example, the internal particle 156 may be enlarged on the processedimage 280. The enlargement processing is intentionally implemented toenhance the sensitivity of detecting particles. The actual particle sizemay be determined by applying a calibration to the image based ontesting samples of known particle sizes.

FIG. 3A depicts a ray diagram of an observer viewing the glass article150 including a particle on the inner wall 152 of the glass article 150.In this embodiment, a particle 310 is attached on the inner wall 152 ofthe glass article 150. When an observer 330 sees the particle 310, theobserver 330 not only directly sees the particle but also sees a virtualimage of the particle 310. The virtual image 320 of the particle 310 iscreated due to a reflection of light on the inner wall 152. The particle310 and the virtual image 320 have mirror symmetry across the inner wall152. Because the particle 310 is attached on the inner wall 152 of theglass article 150, the virtual image 320 also appears to be attached onthe inner wall 152 as shown in FIG. 3A.

FIG. 3B depicts an image of a glass article including a particleaccording to one or more embodiments described and shown herewith. Asshown in FIG. 1, the image 350 is a view from the camera 120 with afocal plane where the polarized light 114 overlaps with the glassarticle 150. The indications of the inner wall 152 and the outer wall154 are included in FIG. 3B for reference only, and the actual image 350may not include the indications of the inner wall 152 and the outer wall154. The optical axis 192 of the camera 120 may be aligned with thelongitudinal axis 190 of the glass article 150. The particle 310 isshown to be attached on the inner wall 152 of the glass article 150 andthe virtual image 320 is also shown to be attached to the inner wall152. Both the particle 310 and the virtual image 320 are located withinthe region of interest 240 defined by the inner circle 206 and the outercircle 208.

The particle 310 and the virtual image 320 may have mirror symmetryacross the inner wall 152 such that the particle 310 and the virtualimage 320 appear to be attached to each other as shown in FIG. 3B.Because the mirror symmetry of a particle and a virtual image thereofattaching to each other is present only when a particle is attached onthe inner wall 152 of the glass article 150, the mirror symmetryindication in an image captured by the camera 120 increasesdetectability of a particle on the inner wall 152 of the glass article150. In addition, the cluster of a particle and a virtual image thereofincreases detectability of the particle of the glass article 150.

When a particle and its virtual image are not attached to each other onan image, it may be determined that the particle is not attached on theinner wall 152 of the glass article 150. For example, as depicted in theimage 360 of FIG. 3C, a particle 340 and a virtual image 350 of theparticle 340 are located within the region of interest 240, but are notattached to each other. In this example, it may be determined that theparticle 340 is not attached to the inner wall 152 of the glass article150.

FIGS. 4A and 4B illustrate comparison between an image captured by aparticle detection system without using polarizers and an image capturedby the present particle detection system using polarizers according toone or more embodiments shown and described herein. FIG. 4A illustratesan exemplary image captured by a camera without using the polarizer 130and the analyzer 140. A light source may be located below the glassarticle 150 (e.g., located at −z direction from the glass article 150)and emit a ring light with a diffuser in a direction parallel to thelongitudinal axis 190 of the glass article 150. The ring light lights upmost of the glass article 150 as shown in FIG. 4A. Thus, it is difficultto detect particles on the glass article 150.

FIG. 4B illustrates an exemplary image captured by the camera 120 usingthe polarizer 130 and the analyzer 140 according to one or moreembodiments shown and described herein. As described above, thepolarization axis of the polarizer 130 is oriented orthogonal to thepolarization axis of the analyzer 140. Thus, the polarizer 130 and theanalyzer 140 working together effectively block reflections from theglass article 150 except for light scattered by particles on the glassarticle 150. The particle 410 may be identified as a white dot at thebottom of the region of interest 240. Because all the background isblack but the particle 410, the particle 410 can be easily identified byhuman eyes or a processor such as the one or more processors 182.

FIGS. 5A and 5B schematically depict a glass particle detection systemaccording to another embodiment shown and described herein. FIG. 5Adepicts a partial side view of the glass particle detection system 500.The glass particle detection system 500 may include a light source 510,a camera 520, a glass article 530, an optical lens 540, and one or morerollers 550. The light source 510 may emit a light beam directed along abeam propagation axis 564. The light beam may be concentrated on a focalplane of the camera 520. Objects that are not on the focal plane may bepoorly lit by the light source 510. The beam propagation axis 564 may beparallel with a longitudinal axis 560 of the glass article 530. Inanother embodiment, the beam propagation axis 564 may not be parallelwith a longitudinal axis 560 of the glass article 530, but the beampropagation axis 564 may be crossed with the longitudinal axis at apoint proximate to an inner wall 534 of the glass article 530.

The light source 510 may emit a coherent light beam using a dark fieldlighting technique. For example, the light source 510 may be a lightsource emitting a laser beam using a dark field lighting technique. Thecoherent light may be directed along the inner wall 534 of the glassarticle 530. Because the light source 510 uses a dark field lightingtechnique, light scattered by particles on the inner wall 534 is readilydetectable by the camera 520, as will be described with reference toFIGS. 7A and 7B below. The light source 510 may be positioned such thatits light beam illuminates any particles on the inner wall 534 of theglass article 530. This ensures that particles on the inner wall 534 arewell-illuminated and minimizes the illumination of external particles,e.g., particles on the outer wall 532 of the glass article 530.

The camera 520 may be a line scan camera. The camera 520 may have afocal plane which overlaps with an inner wall 534 of the glass article530. The camera 520 includes an optical lens 522. The optical lens 522may have a depth-of-field that is approximately 75% of the thickness ofthe wall of the glass article 530. For example, the optical lens 522 mayhave approximately a 300 micrometer depth-of-field. The optical axis 562of the camera 520 may be orthogonal to the beam propagation axis 564 ofthe light source 510 and the longitudinal axis 560 of the glass article530. In another embodiment, the optical axis 562 may not be orthogonalto the beam propagation axis 564 of the light source 510. For example,an angle between the optical axis 562 and the beam propagation axis 564may be less than 90 degrees.

The glass article 530 may have a cylindrical shape such as tubes,syringes, vials, etc. The glass article 530 has the longitudinal axis560 which is parallel to the x axis of FIG. 5A. The glass article 530may be placed on one or more rollers 550. The one or more rollers 550rotate around their central axis 552 to rotate the glass article 530. Asthe glass article 530 rotates, the camera 520 may scan images throughoutthe inner wall 534. Once the glass article 530 rotates about 360degrees, the camera 520 may process and synthesize the captured imagesto prepare a single integrated image that corresponds to the entireinner wall of the glass article 530. For example, by synchronizing therotation of the glass article 530 and the frame capture of the glassarticle 530, an image of the inner wall 534 of the glass article 530 maybe built up line-by-line. All the images corresponding to the inner wall534 of the glass article 530 may be integrated to a full 2Drepresentation of the 3D surface of the glass article 530. The camera520 may communicate with the computing device 180 in a similar way asdescribed with reference to FIG. 1. The optical lens 540 may be acollimating lens which collimates a light beam from the light source 510to illuminate only the inner wall 534 of the glass article 530.

FIG. 5B depicts a front view of the glass particle detection system 500according to one or more embodiments shown and described herein. In thisembodiment, the glass article 530 is placed on two rollers 550. The tworollers 550 rotate around their central axis 552, and thereby rotatingthe glass article 530. The camera 520 may capture an image at a focalplane 570 of the camera 520. The two rollers 550 may rotate eitherclockwise or counterclockwise. Although two rollers are shown in FIG.5B, more than two rollers or less than two rollers may be used to rotatethe glass article 530.

FIG. 6 depicts camera configuration for determining the location ofparticles on a glass article according to one or more embodimentsdescribed and shown herewith. In this embodiment, an external particle630 may be located on the outer wall 532 of the glass article 530, andan internal particle 620 may be located on the inner wall 534 of theglass article 530. The camera 520 may have a focal plane (not shown)which is located proximate to the inner wall 534 of the glass article530. The camera 520 may have a field of view 610. The camera 520 mayhave a depth-of-field 640 which may be, e.g., less than 300 micrometers.In this embodiment, the internal particle 620 may be located within thefocal plane of the camera 520 and the external particle 630 may belocated outside the focal plane. In addition, the light source 510 mayemit a collimating light illuminating the inner wall 534 of the glassarticle 530. Thus, an image of the external particle 630 captured by thecamera 520 may be out of focus and poorly illuminated whereas an imageof the internal particle 620 captured by the camera 520 may be in focusand well-illuminated.

The camera 520 may transmit the captured image to the computing device180. The computing device 180 may determine whether the captured imageincludes particles in focus. If it is determined that the captured imageincludes particles in focus, the one or more processors 182 maydetermine that the particle is attached to the inner wall 534 of theglass article 530. The one or more processors 182 may indicate that theglass article 530 should be rejected based on the determination. Theindication of rejection may be stored in the one or more memory modules184 along with the identification of the glass article 530. If it isdetermined that the captured image does not include any particle infocus, the one or more processors 182 may determine that no particle ispresent on the inner wall 534 of the glass article 530. Thedetermination may be stored in the one or more memory modules 184 alongwith the identification of the glass article 530.

FIGS. 7A-7B depict light reflection on particles of a glass articleaccording to one or more embodiments described and shown herewith. InFIG. 7A, the light source 510 may emit a light beam 512 along the beampropagation axis 564. The beam propagation axis 564 may be parallel withthe longitudinal axis 560 of the glass article 530. The optical lens 540may collimate the light beam 512 and emit a collimated light beam 514.The collimated light beam 514 illuminates the inner wall 534 of theglass article 530. The collimated light beam 514 is scattered by theinternal particle 620 and a portion of the scattered light may bedirected towards the camera 520 (+z direction). Thus, the camera 520 maycapture the portion of the scattered light from the internal particle620.

In FIG. 7B, the light source 510 may emit a light beam 512 along thebeam propagation axis 564. The beam propagation axis 564 may be parallelwith the longitudinal axis 560 of the glass article 530 and aligned withthe wall of the glass article 530. The optical lens 540 may collimatethe light beam 512 and output a collimated light beam 514. Thecollimated light beam 514 illuminates the inner wall 534 of the glassarticle 530. Because the external particle 630 is located on the outerwall 532 of the glass article 530, the collimated light beam 514 rarelyreaches the external particle 630. In addition, even if a portion of thecollimated light beam 514 reaches the external particle 630, the lightreflected from the external particle 630 would not be directed towardthe camera 520. In this regard, the camera 520 may capture scatteredlight only from particles located on the inner wall 534 of the glassarticle 530.

The camera 520 may transmit the captured image to the computing device180. The computing device 180 may determine whether the captured imageincludes any particle. If it is determined that the captured imageincludes a particle, the one or more processors 182 may determine thatthe particle is attached to the inner wall 534 of the glass article 530.The one or more processors 182 may indicate that the glass article 530should be rejected based on the determination. The indication ofrejection may be stored in the one or more memory modules 184 along withthe identification of the glass article 530. If it is determined thatthe captured image does not include any particle, the one or moreprocessors 182 may determine that no particle is present on the innerwall 534 of the glass article 530. The determination may be stored inthe one or more memory modules 184 along with the identification of theglass article 530.

FIGS. 8A and 8B depict comparison between a captured image using abacklighting and a captured image using a laser dark field illumination.FIG. 8A depicts a sample image captured by a camera using a backlightingilluminating a glass article 530. In this example, the backlighting maybe located below the glass article 530 (e.g., located at −z directionfrom the glass article 530). The glass article 530 includes bothexternal particles 630 on the outer wall 532 and internal particles 620on the inner wall 534. Both external particles 630 and the internalparticles 620 are illuminated by the backlighting. The externalparticles 630 are captured by the camera 520 out of focus whereas theinternal particles 620 are captured by the camera 520 in focus becauseonly the internal particles 620 are located within the focal plane ofthe camera 520. However, it is difficult and takes time to distinguishthe external particles from the internal particles on the sample imageitself because the sample image includes illuminations from both theinternal particles and the external particles.

FIG. 8B depicts a sample image captured by a camera using a light sourcewhich directs a light beam proximate to the inner wall 534 of the glassarticle 530 as shown in FIG. 5A. The light source 510 may be a lightbeam with laser dark field illumination. In this sample image of FIG.8B, the internal particles 620 are well-lit whereas the externalparticles are not visible. Thus, in this sample image, it is much easierand convenient to determine whether internal particles 620 are presentin a glass article. For example, the one or more processors 182determines that the sample image of FIG. 8B includes particles 620, anddetermines that the particles 620 are attached to the inner wall 534 ofthe glass article 530. Then, the one or more processors 182 indicatethat the glass article 530 should be rejected based on thedetermination.

FIG. 9 schematically depicts a glass particle detection system accordingto another embodiment shown and described herein. The glass particledetection system includes a ring light source 930, a camera 120, apolarizer 130, an analyzer 140, a glass article 150, and a beam splitter910. The glass article 150 may be a cylindrically-shaped glass such as atube, a syringe, a vial, etc. The glass article 150 has a longitudinalaxis 190 which is parallel with the z axis of FIG. 9. The glass articlemay be fixed to a holder 160 which is attached to a linear actuator 170.

The ring light source 930 may be a laser emitting a ring light 920 alongthe beam propagation axis 912. The beam propagation axis 912 may beparallel with the x axis of FIG. 9. The beam propagation axis 912 may beperpendicular to the longitudinal axis 190 of the glass article 150. Insome embodiments, the beam propagation axis 912 may not be perpendicularto the longitudinal axis 190 of the glass article 150. For example, theangle between the beam propagation axis 912 and the longitudinal axis190 may be less than 90 degrees. The diameter of the ring light 920 maybe about the same as the diameter of the inner wall 152 of the glassarticle 150. The polarizer 130 may be positioned between the lightsource 110 and the beam splitter 910 such that the ring light 920 fromthe ring light source 930 passes through the polarizer 130 at a normaldirection. The polarizer 130 polarizes the non-polarized ring light 920according to the polarization axis of the polarizer 130 and outputs apolarized ring light 922. The polarized ring light 922 may produce lessglare when reflecting on the glass article 150 compared to thenon-polarized ring light 920.

The beam splitter 910 changes the propagation direction of the polarizedring light 922 and directs the polarized ring light 922 into the glassarticle 150 while still allowing the camera 120 to image the internalsurface of the glass article 150. The outer diameter of the polarizedring light 922 may be matched to the diameter of the inner wall 152 ofthe glass article 150.

The glass article 150 may scatter the polarized ring light 922. If theglass article 150 includes any particles, the polarized ring light 922may be scattered by the particles. The polarization direction of thepolarized ring light 922 is changed when the polarized ring light 922 isscattered by the particles. In this embodiment, the glass article 150may have an internal particle 156 attached on the inner wall 152 of theglass article 150 and an external particle 158 attached on the outerwall 154 of the glass article 150. The polarized ring light 922 isscattered by the internal particle 156. In contrast, the polarized ringlight 922 is not scattered by the external particle 158 because thepolarized ring light 922 may not reach the external particle 158.

The polarization direction of the scattered light may be changed. Forexample, the polarized ring light 922 that was scattered by the internalparticle 156 is polarized in a direction that is different from thepolarization direction of the polarized ring light 922. In contrast, thepolarization direction of the polarized ring light 922 is not changedwhen it reflects on the glass article 150 where no particle is presentat the reflection region. For example, the light 926 which was reflectedfrom the glass article 150 is polarized in the same direction as thepolarized ring light 922.

In contrast, the polarized ring light 922 from the ring light source 930may not be scattered by the external particle 158 because the polarizedring light 922 may rarely reach the external particle 158. In addition,even if a portion of the polarized ring light 922 reaches the externalparticle 158, the light reflected from the external particle 158 wouldnot be directed toward the camera 120.

The analyzer 140 is positioned between the beam splitter 910 and thecamera 120. The analyzer 140 may be a polarizer that polarizes anincident light. The analyzer 140 may have similar light opticalcharacteristics (e.g., polarization) as the polarizer 130. Thepolarization axis of the analyzer 140 may be oriented to a differentdirection than the polarization axis of the polarizer 130. For example,the polarization axis of the analyzer 140 may be oriented at about ±90degrees relative to the polarization axis of the polarizer 130. Thus,the ring light 922 polarized according to the polarization axis of thepolarizer 130 cannot pass through the analyzer 140 because the ringlight 922 is polarized in a direction orthogonal to the polarizationaxis of the analyzer 140. Similarly, the light 926 which was reflectedfrom the glass article 150 cannot pass through the analyzer 140 becausethe light 926 is polarized in a direction orthogonal to the polarizationaxis of the analyzer 140.

In contrast, the light 924 that was scattered by the internal particle156 is polarized in a direction that is not orthogonal to thepolarization axis of the polarized ring light 922. For example, if thering light 922 is polarized according to the polarization axis of thepolarizer 130, the polarization direction of the light 924 may bedifferent from the polarization axis of the polarizer 130, but notorthogonal to the polarization axis of the analyzer 140. Thus, a portionof the light 924 would pass through the analyzer 140 because thedifference between the polarization direction of the light 924 and thepolarization axis of the analyzer 140 is not 90 degrees, i.e., notorthogonal. In this regard, only light that is scattered by particles onthe inner wall 152 of the glass article 150 can pass through theanalyzer 140.

The camera 120 may capture an image of the ring light reflected from theglass article 150. The camera 120 may be any device having an array ofsensing devices capable of detecting radiation in an ultravioletwavelength band, a visible light wavelength band, or an infraredwavelength band. The camera 120 may have a focal plane that may beparallel to the x-y plane of FIG. 9 and cross the glass article 150. Thecamera 120 may include an optical lens 122. The optical axis of thecamera may be perpendicular to the beam propagation axis 912. Theoptical axis 192 of the camera 120 may be parallel with the longitudinalaxis 190 of the glass article 150. In some embodiments, the optical axis192 of the camera 120 may be co-located with the longitudinal axis ofthe glass article 150. In another embodiment, the optical axis 192 ofthe camera 120 may not be parallel with the longitudinal axis 190 of theglass article 150, but the optical axis 192 may be crossed with thelongitudinal axis 190 of the glass article at a point proximate to thefocal plane of the camera 120. The camera 120 may capture an image ofthe ring light on the focal plane which, for example, includes theinternal particle 156 as illustrated in FIG. 10. The camera 120 maycommunicate with the computing device 180 in a similar way as describedwith reference to FIG. 1.

The linear actuator 170 may move in a vertical direction (+/−zdirection) to move the glass article 150 in the vertical direction. Asthe linear actuator 170 moves glass article 150 in the verticaldirection, the focal plane of the camera 120 may be placed on differentcross-sections of the glass article 150 in terms of the verticaldirection (+/−z direction). Thus, the camera 120 can capture images ofthe ring light reflected from each and every wall of the glass article150.

FIG. 10 depicts an image of the ring light reflected from the glassarticle. In this embodiment, the image 1000 illustrates a view of afocal plane of the camera 120. The image 1000 may depict the inner wall152 and the outer wall 154 of the glass article 150, a region ofinterest 240, and an internal particle 156.

The outer wall 154 and the inner wall 152 may be illustrated in theimage 1000 in FIG. 10 for reference only, and the actual image may notinclude the outer wall 154 and the inner wall 152. As described above,because the polarization direction of the ring light scattered by theinternal particle 156 is changed, the light scattered by the internalparticle 156 can pass through the analyzer 140 and reach the camera 120.Thus, the internal particle 156 may be visible to the camera 120. Incontrast, the external particle 158 is not shown in the image 1000because the polarized ring light 922 is rarely scattered by the externalparticle 158 as discussed above. In this regard, the image 1000 may onlycapture particles on the inner wall 152 of the glass article 150.

The indication of the region of interest 240 may be embedded to theimage 1000 in order to facilitate determining whether a particle ispresent on the inner wall of the glass article 150. In embodiments, theone or more processors 182 may determine whether any particle is presentwithin the region of interest 240 of the image captured by the camera120. If it is determined that a particle is present within the region ofinterest 240, the one or more processors 182 may determine that theparticle is attached to the inner wall of the glass article 150. The oneor more processors 182 may indicate that the glass article 150 should berejected based on the determination. The indication of rejection may bestored in the one or more memory modules 184 along with theidentification of the glass article 150. If it is determined that noparticle is present within the region of interest 240, the one or moreprocessors 182 may determine that no particle is present on the innerwall of the glass article 150. The determination may be stored in theone or more memory modules 184 along with the identification of theglass article 150.

According to one or more embodiments of the present disclosure, thecombination of the lighting and optics geometry allows for accuratedetection of internal particles of a glass article. The light and opticsgeometry produces a virtual image of a particle as shown in FIGS. 3A and3B, which not only increases particle detectability but also enhancesaccuracy of determination whether a particle is attached on the innerwall of a glass article. In addition, with the lighting optics geometry,the detection of particles on inner walls of glass articles may beautomated. For example, 80 glass articles per minute can be examinedwhether they have particles on inner walls of glass articles. Thepresent light and optics geometry may be used for different sizes anddimensions of glasses. For example, the present method may be applied toglass articles with different thicknesses and/or shapes. Furthermore,because the present detection systems focus on detecting particles onthe inner walls of glass articles and reject those glass articles withinternal particles, glass articles that only include external particlesare not rejected altogether in the process of testing glass articles.Thus, the present detection method improves glass article yield andsaves costs.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. Itwill be further understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order, nor that with any apparatus specificorientations be required. Accordingly, where a method claim does notactually recite an order to be followed by its steps, or that anyapparatus claim does not actually recite an order or orientation toindividual components, or it is not otherwise specifically stated in theclaims or description that the steps are to be limited to a specificorder, or that a specific order or orientation to components of anapparatus is not recited, it is in no way intended that an order ororientation be inferred, in any respect. This holds for any possiblenon-express basis for interpretation, including: matters of logic withrespect to arrangement of steps, operational flow, order of components,or orientation of components; plain meaning derived from grammaticalorganization or punctuation, and; the number or type of embodimentsdescribed in the specification.

As used herein, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “a” component includes aspects having two or moresuch components, unless the context clearly indicates otherwise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A glass particle detection system, comprising: alight source configured to emit a light beam into a cylindrical glassarticle when the cylindrical glass article is imaged by the glassparticle detection system, the light beam being directed along a beampropagation axis that is perpendicular to a longitudinal axis of thecylindrical glass article; a polarizer positioned between the lightsource and the cylindrical glass article; a camera configured to capturean image of the light beam reflected from the cylindrical glass article,an optical axis of the camera being perpendicular to the beampropagation axis of the light source; an analyzer positioned between thecylindrical glass article and the camera; and a computing devicecommunicatively coupled to the camera, the computing device comprisingat least one processor and at least one memory storing computer readableand executable instructions that, when executed by the at least oneprocessor, cause the computing device to: determine boundaries of aninner wall and an outer wall of the cylindrical glass article based onthe captured image; determine a region of interest based on theboundaries; and determine whether a particle is present within theregion of interest.
 2. The glass particle detection system of claim 1,wherein a polarization axis of the polarizer is oriented at about 90degrees relative to a polarization axis of the analyzer.
 3. The glassparticle detection system of claim 1, wherein the light source is alaser light source.
 4. The glass particle detection system of claim 1,further comprising: a holder for holding the cylindrical glass article;and an actuator coupled to the holder and configured to move the holderin a direction parallel to the longitudinal axis of the cylindricalglass article.
 5. The glass particle detection system of claim 1,wherein the computer readable and executable instructions, when executedby the processor, cause the computing device to determine that aparticle is attached to the inner wall of the cylindrical glass articleif it is determined that the particle is present within the region ofinterest.
 6. The glass particle detection system of claim 1, wherein thecomputer readable and executable instructions, when executed by theprocessor, cause the computing device to determine that no particle isattached to the inner wall of the cylindrical glass article if it isdetermined that no particle is present within the region of interest. 7.The glass particle detection system of claim 1, wherein the region ofinterest is defined by an inner circle and an outer circle, a center ofthe inner circle is the same as a center of the outer circle, a radiusof the outer circle is less than a radius of the outer wall of thecylindrical glass article and more than a radius of the inner wall ofthe cylindrical glass article, and a radius of the inner circle is lessthan a radius of the inner wall of the cylindrical glass article.
 8. Theglass particle detection system of claim 7, wherein the radius of theinner circle is between about 90% of the radius of the inner wall andabout 95% of the radius of the inner wall.
 9. A method for detectingparticles on a cylindrical glass article, comprising: directing a lightbeam through a polarizer into the cylindrical glass article along a beampropagation axis that is perpendicular to a longitudinal axis of thecylindrical glass article, the light beam polarized by the polarizerproducing light scattered by one or more particles on the inner wall ofthe cylindrical glass article; capturing, by a camera having an opticalaxis perpendicular to the beam propagation axis, an image of the lightbeam reflected from the cylindrical glass article including thescattered light via an analyzer, the analyzer located between thecylindrical glass article and the camera, and a polarization axis of thepolarizer being oriented at about 90 degrees relative to a polarizationaxis of the analyzer; determining boundaries of the inner wall and anouter wall of the cylindrical glass article on the image; determining aregion of interest based on the boundaries; processing the image tofilter out illumination outside the region of interest; and determiningwhether a particle is present within the region of interest.
 10. Themethod of claim 9, further comprising determining that a particle isattached to the inner wall of the cylindrical glass article if it isdetermined that the particle is present within the region of interest.11. The method of claim 9, further comprising determining that noparticle is attached to the inner wall of the cylindrical glass articleif it is determined that no particle is present within the region ofinterest.
 12. The method of claim 9, wherein the region of interest isdefined by an inner circle and an outer circle, a center of the innercircle is the same as a center of the outer circle, a radius of theouter circle is less than a radius of an outer wall of the cylindricalglass article and more than a radius of an inner wall of the cylindricalglass article, and a radius of the inner circle is less than a radius ofthe inner wall of the cylindrical glass article.
 13. The method of claim9, wherein the optical axis of the camera is parallel with thelongitudinal axis of the cylindrical glass article.
 14. The method ofclaim 9, further comprising moving, by an actuator, the cylindricalglass article in a direction parallel to the longitudinal axis of thecylindrical glass article.